Cylindrical granule made of biocompatible metal material for vertebroplasty

Abstract

A cylindrical granule made of a biocompatible metal material, in particular titanium or its alloys, for vertebroplasty operations has a cylindrical shape and includes a central cylindrical body connected at its ends to a first disc and to a second disc respectively, and a portion with a trabeculated structure, which extends around the central cylindrical body between the lower surface of the first disc and the upper surface of the second disc.

Claims

1. A cylindrical granule made of a biocompatible metallic material for vertebroplasty operations, the cylindrical granule having a cylindrical shape and a central cylindrical body, the central cylindrical body having an upper end connected to a first disk and a lower end connected to a second disk; and a portion with a trabeculated structure which extends around said central cylindrical body between a lower surface of said first disk and an upper surface of said second disk.

2. The cylindrical granule according to claim 1, wherein said central cylindrical body has a solid structure.

3. The cylindrical granule according to claim 1, wherein said first disk and said second disk have a solid structure.

4. The cylindrical granule according to claim 1, wherein an external diameter of said cylindrical granule, corresponding to a diameter of said first and said second discs, is less than 4 mm.

5. The cylindrical granule according to claim 4, wherein said external diameter of said cylindrical granule is comprised between 3 and 4 mm.

6. The cylindrical granule according to claim 4, wherein said external diameter of said cylindrical granule is equal to 3.3 mm.

7. The cylindrical granule according to claim 1, wherein said cylindrical granule is manufactured using electron beam melting (EBM) rapid prototyping.

8. The cylindrical granule according to claim 1, wherein said portion having with a trabeculated structure has an average porosity of between 400 and 800 microns.

9. The cylindrical granule according to claim 1, wherein said portion with a trabeculated structure has a trabeculation made by EBM formed by dode-thin elements.

Description

LIST OF FIGURES

[0022] The characteristics and advantages of the biocompatible metal granule for vertebroplasty according to the present invention will be even more evident from the following detailed description, provided in an exemplary and non-limiting form, referring to the attached schematic drawings in which:

[0023] FIG. 1 shows an overall perspective view of the cylindrical granule made of biocompatible metal material according to the present invention;

[0024] FIG. 2 shows a view of the full solid structure only of the granule of FIG. 1 from which the trabeculated portion has been removed;

[0025] FIG. 3 shows an enlarged schematic representation of the trabeculated portion only of the granule of FIG. 1;

[0026] FIG. 4 shows a detail of the trabeculated portion of FIG. 3;

[0027] FIGS. 5A and 5B and FIGS. 6A and 6B show the dode-thin structure, of the known type, of the trabeculation of the cylindrical granule according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0028] The cylindrical granule according to the present invention is made of biocompatible metal material, more particularly in metal materials based on titanium and/or its alloys, and are produced with such characteristics as to simultaneously allow insertion during the operating phase inside the main body of the vertebra, resistance to primary loads, osteointegration of the granules over time and the stimulation of bone re-growth.

[0029] The specific cylindrical conformation of the granule 10 according to the present invention advantageously optimizes the insertion step of the granule into the vertebra to be repaired which can take place by means of a cannula, preferably the same cannula with which the surgeon inserts the balloon inside the main body of the vertebra.

[0030] This cannula has a reduced diameter, which therefore imposes the maximum diameter of the granules. At the same time, the granules must have such dimensions that once inserted inside the vertebra, they do not move and do not exit through any bone shortages that may occur in the walls of the body of the vertebra as a result of vertebral damage.

[0031] The granules 10 according to the present invention have a substantially cylindrical shape, and have a central cylindrical body 13 connected, at its ends, to a first disc 11 and to a second disc 12 respectively, said discs 11, 12 lying on a plane substantially orthogonal to the longitudinal axis of said central cylindrical body 13.

[0032] The external diameter C of the cylindrical granule 10, which coincides with the diameter of the discs 11 and 12, is preferably less than 4 mm, more preferably ranging from 3 to 4 mm, even more preferably 3.3 mm.

[0033] Said central cylindrical body 13 and said first disc 11 and second disc 12 have a solid structure made of a biocompatible metal material, preferably titanium or its alloys.

[0034] According to what can be seen by way of example in the attached figures, and in particular in the enlarged partial views of FIGS. 3 and 4, the cylindrical granule 10 according to the present invention comprises a portion having a trabeculated structure 14 which extends around said central cylindrical body 13 extending between the internal surface 11a of said first disc 11 and the external surface 12a of said second disc 12, around said central cylindrical body 13.

[0035] Said trabeculated portion 14 advantageously extends around said central cylindrical body 13 remaining within the cylindrical shape defined by the two end discs 11, 12 of the granule itself, according to what can be seen for example in FIG. 1.

[0036] The cylindrical granule 10 according to the present invention is advantageously produced by means of production techniques which provide for the localized casting of powders (metal or polymeric powders) by means of high-energy electron beams.

[0037] These techniques, known as EBM, acronym of Electron Beam Melting, are today extremely advanced manufacturing technologies that allow the creation of objects also having an extremely complex geometry and with different surface roughnesses starting from a computer drawing of the finished product, which is processed by computerized machines that guide the electron beam in its action.

[0038] Electron beam melting is a relatively new rapid prototyping technique for the production of implant structures, and allows the production of complex three-dimensional geometries.

[0039] Using this technique, the present Applicant has perfected the cylindrical granule 10 object of the present invention in which the part having a regular trabecular structure 14, with a pore size between one trabecula and the other in the order of a hundred microns.

[0040] More specifically, the regular trabecular structure 14 will have a pore diameter ranging from 400 to 800 microns, even more preferably the pore diameter will be about 600 microns, preferably 640 microns.

[0041] The trabecular structure 14 in titanium or titanium alloys, in particular, thanks to an elastic modulus very close to that of the natural trabecular bone, restores the physiological transfer of loads, avoiding damage to the bone and actually favouring its re-growth.

[0042] With respect to the specific configuration of the cylindrical granule 10 according to the present invention, the area having a trabeculated structure 14 which involves at least a portion of said granule 10 which extends around said central cylindrical body 13, between said first disc 11 and said second disc 11, will advantageously have a trabeculated structure created through the EBM production process that uses the known type of software element called “dode-thin”.

[0043] With particular reference to FIG. 3, this shows a portion of the trabeculated structure comprising a “dode-thin” mesh, whereas FIG. 5A shows the orientation of the “dode-thin” element corresponding to the hexahedral geometry shown in FIG. 5B, which there is in correspondence with the faces of the three-dimensional trabeculated structure, and FIG. 6A shows the orientation of the “dode-thin” element corresponding to the octahedral geometry shown in FIG. 6B which there is in correspondence with the diagonals (at 45°) of the three-dimensional trabeculated structure.

[0044] The CAD-CAM software implement the mesh according to the “dode-thin” elements, of a known type, starting from a drawing showing a level of detail as illustrated, for example, in FIGS. 3 and 4, finally arriving at a product, obtained through EBM techniques, as shown in FIG. 1.

[0045] The Applicant has also verified that the particular configuration of the cylindrical granule 10 according to the present invention, and in particular the presence of a central cylindrical body 13 having a full solid structure connected at its ends to a first disc 11 and to a second disc 11 also having a full solid structure, and of the wide trabeculated area 14 which extends around said central cylindrical body 13, allows an optimal mechanical behaviour to be obtained in the in-vivo implant for supporting loads, immediately obtaining the primary stability of the implant, both for the structure of the granules themselves and for the shape that allows an interlocking between adjacent granules.

[0046] Furthermore, as already mentioned, the cylindrical shape facilitates the insertion of the granules 10 into the vertebra through a surgical cannula, preferably the same cannula used by the surgeon for the insertion of the balloon into the body of the vertebra, thus avoiding having to extract and re insert the cannula in order to perform the two operations for inserting the balloon and the granules.

[0047] From the description provided so far, the features of the cylindrical granule made of biocompatible metal material, in particular titanium or its alloys, to be used in vertebroplasty operations according to the present invention are evident, as also the relative advantages.

[0048] It is understood that the cylindrical granule for vertebroplasty operations thus conceived can undergo modifications and/or variations, all falling within the invention whose protection scope is defined by the enclosed claims.

[0049] In particular, the materials described, as also the dimensions, may vary according to requirements.